When the traffic lights turn red, we will stop driving a car or crossing a street. Why is red used for traffic lights instead of other colors?
As we know, scattering(散射) happens when light goes through the air. For the same media(媒质), if the wavelength islong, the scattering will be short. If the wavelength is short, then the scattering will be long.
Of all lights we can see red has the longest wavelength, so the scattering is the weakest. That means the red light travels far. In fact, it travels farther on rainy days.
Using the red light can help drivers in farther areas sec the lights. It helps drivers stow down or stop in lime. If drivers don't see the red light until they are close, they may not be able to stop the car in time. An accident may happen Red can also excite people. We can act more quickly when we see the color red. In a word, red lights help drivers stop in time and help prevent accidents.
【小题1】 When the traffic lights turn ______, we will stop driving a car.
A. red    B green     C. yellow
【小题2】According to the passage, the scattering of the red light is the _______.
A. longest    b. weakest       C. farthest
【小题3】 The underlined word "wavelength" means________ in Chinese.
A.波浪        B.光波      C.波长
【小题4】 What can the red light help drivers do?
A. It can help drivers in farther areas see the lights.
b. It can help drivers slow down or stop in time.
C.A and b
【小题5】Which of the following is the best title?
A. Why do accidents happen
b. How does the red light travel
C. Why do we use red traffic lights

 Let me tell you ________.

A. how much is the car                                           B. how much does the car cost

C. how much did I pay for the car                         D. how much I spent on the car

 

When the traffic lights turn red, we will stop driving a car or crossing a street. Why is red used for traffic lights instead of other colors?

As we know, scattering (散射) happens when light goes through the air. For the same media(媒质), if the wavelength is long, the scattering will be short. If the wavelength is short, then the scattering will be long.

Of all lights we can see red has the longest wavelength, so the scattering is the weakest. That means the red light travels far. In fact, it travels farther on rainy days.

Using the red light can help drivers in farther areas sec the lights. It helps drivers stow down or stop in lime. If drivers don't see the red light until they are close, they may not be able to stop the car in time. An accident may happen Red can also excite people. We can act more quickly when we see the color red. In a word, red lights help drivers stop in time and help prevent accidents.

1. When the traffic lights turn ______, we will stop driving a car.

A. red    B green     C. yellow

2.According to the passage, the scattering of the red light is the _______.

A. longest    b. weakest       C. farthest

3. The underlined word "wavelength" means________ in Chinese.

A.波浪        B.光波      C.波长

4. What can the red light help drivers do?

A. It can help drivers in farther areas see the lights.

b. It can help drivers slow down or stop in time.

C. A and b

5.Which of the following is the best title?

A. Why do accidents happen

b. How does the red light travel

C. Why do we use red traffic lights

 

Let me tell you ________.

A. how much is the car                                           B. how much does the car cost

C. how much did I pay for the car                         D. how much I spent on the car

 

We have a two-day holiday every week. We don’t have any lessons on Saturdays or Sundays, so every weekend I have a good time.

On weekends, I like taking a trip. I sometimes go to the country with my classmates by bus to breathe(呼吸)the fresh air, watch the green hills and the blue sea, and walk in the beauty of the countryside. Sometimes I go for a picnic in the open air with my friends by bike. There we draw many pictures and take photos. Sometimes I go to visit a place of interest with my parents by car.

Sometimes on Saturdays, I take a long trip with my parents. We don’t go home at night and make a fire on the hill. We sit around it, singing and dancing happily. If we feel tired, we get together, look at the stars and chat for a long time, and then sleep for a few hours.

My weekends are always full of interest and happiness.

根据短文内容，回答下列问题。

1.Why does the writer have a good time every weekend?

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2.What’s the meaning of the underlined word“beauty”in Chinese?

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3.How does the writer go for a picnic?

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4.If the writer and his parents feel tired, what do they do?

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5.Do you have a two-day holiday every week? If so, what do you often do?

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